Phytophthora elongata (Peronosporaceae) is present as an estuarine species in Philippine mangroves

The genus Phytophthora, a group of hemibiotrophic oomycetes, is composed of almost 150 species, most of which are pathogens of terrestrial and freshwater plant species. Of the known taxa of Phytophthora, three species (P. estuarina, P. gemini, and P. rhizophorae) were only recorded in the estuarine or marine environment, while others were recently discovered to be present in these environments as saprotrophs, suggesting that more Phytophthora species might be present in marine or estuarine habitats. Thus, mangrove habitats of the Philippines were surveyed for additional Phytophthora species apart from the previously-reported species, Phytophthora insolita. As a result, Phytophthora elongata, which was reported as a pathogen of Eucalyptus marginata from Western Australia, was isolated from mangrove leaf litter in the coastal area of Cavite, Philippines, as the first Clade 2 species found in saline habitats. This suggests that among Phytophthora species there is the potential to rather easily evolve measures to deal with osmotic pressure, which supports the potential importance of mangroves as a cryptic habitat of Phytophthora.